It is freezing cold, wet, and impenetrably dark. Visibility is zero: you can see nothing at all. You have no sense of direction; you cannot even tell up from down. This is a lifeless place, not even the lowliest insect or the most insignificant lichen. You are alone, underground and underwater, and cold. No one has ever been here before. Progress, such as it is, is by what slight sense of touch is possible through thick gloves, necessary to keep your hands from freezing to disabling numbness. The only way back to safety is by means of a thin lifeline you tied at the entrance and laid out behind you. The way forward is unknown.

This is cave diving, readily acknowledged by the hardiest of mountain climbers and the most fearless bungee jumpers as the world's most dangerous leisure activity.

This was the scene in 1983 when Welshman Martyn Farr entered Crag Cave near Castleisland in County Kerry. He was heavily laden with the very cumbersome paraphernalia essential for cave diving. The cave diver must wear two complete sets of unwieldy life-support equipment, one as an emergency backup. Two reliable torches are the minimum, three is more normal. Wetsuits or drysuits, weight belt, knife, hammer, depth gauge, decompression meter and the indispensable helmet complete the picture. The tenuous lifeline is crucial for a safe exit; it could break, or tear against the jagged rock; you could drop it. If you lose this feeble contact you have little likelihood of negotiating the return journey through an unmapped labyrinth of dark and muddy water-filled passages and chambers.

On that fateful day, Farr, an experienced speleologist (cave explorer), started his journey in a dry cave that was known in the area for generations. A small pool marked the end of previous explorations. It was called the Green Lake. The water was clear, but experience had taught him that his presence would soon stir up the ever-present sediment, instantly reducing visibility to nil. He had no way of knowing what was ahead, how far would he have to go, how deep the water would be.
He followed the underwater passage, the depth a mere two metres, but without the reassurance of a surface overhead.

In the event, his journey was short. After a mere seven metres of line, he broke surface and emerged in the absolute darkness of a cavern. His powerful lights unveiled a scene that had never before been seen by anyone. He was in a huge grotto abounding with thousands of stalactites and stalagmites. He named it Divers Delight.

Exploration of the cavern, eroded from the limestone by rivers that have vanished tens of thousands of years ago, continued over a number of years. Each gallery and tunnel was named from scenes in Tolkien's fantasy, "Lord of the Rings", and it is indeed reminiscent of the enchanting images in the book. It was quickly discovered that there had been another entrance at some distant time in prehistory - huge boulders filled an enormous hole in the ground that had once been a natural opening.

Work soon began on clearing the tons of rock and replacing it with a staircase to the cave sixty feet below ground level. Lights were installed, carefully supervised by Michael Scott of the Irish National Theatre, a former Artistic Director of the Dublin Theatre Festival. Paths were painstakingly laid and barriers erected, discerningly placed to protect the visitor from danger and - perhaps more importantly - to protect the delicate formations from the visitor.
Crag Cave has now been explored for nearly four kilometres. Three hundred and fifty metres of this is open to the public on guided tours. The centre has a restaurant and gift shop.

The temptation to compare the cave to Ailwee in the Burren of County Clare is difficult to resist, but comparisons are not easy; the caves are very different. Ailwee is longer, but Crag has such an affluence of stalactites and stalagmites of all shapes and sizes that the huge caverns assume a fairytale enchantment. The subtle lighting enhances the spell but the staid background music is a mistake, intruding on the intimacy of a visit to this exotic place.

There are numerous caverns and galleries, opening one into another in ever more splendid magnificence. Knowing that this is but a small part of a labyrinth of passages and tunnels, stretching for four kilometres or more, is mesmerising. The temptation to sneak away from the tour party and crawl into one of the tunnels is great, but beyond the ostensible innocence of such an entrance lies a lonely darkness as dead as dinosaurs.

Great pains have been taken to preserve the fragile straw stalactites from acquisitive souvenir hunters, but the planners have thoughtfully declared open season on one large specimen, allowing each visitor to touch and feel this beautiful substance which nature has taken so long to produce. Estimates vary on the rate of growth but it is measured in millimetres per century. When one wonders at those which are several metres in length, the stillness of time in this subterranean realm becomes real.

Crag Cave has fixed Castleisland firmly on the tourist map. More than thousand visitors have come since it opened to the public in It is owned by the Geaney family, who spent more than £500,000 in developing the complex. It the only major tourist attraction in this part of the Kingdom but it has become Kerry's compulsory stopover for tourists and school tours alike. And when the Lakes of Killarney don't look quite their best on extra soft days or Fungie the Dingle dolphin is shielded from his human visitors by Atlantic storms, the cave is just the ticket, the temperature inside being constant throughout the year at about ten degrees.

Admission to the cave is €12 for adults but even this modest sum will be waived, on condition that you use the same entrance Martyn Farr used on that first fateful visit. Most of us will cheerfully part with our cash for the simpler option of paying at the gate.

Manhattan is the home of dire warnings: this is no place for the faint-hearted. They tell you that driving cars in this madhouse should be left to the cabbies. Survival rates for the stranger are said to be slight.

The worst warnings came from the new natives - those living in the Big Apple for nearly a year; they know everything. They warn against getting behind the wheel because it is mad, and anyway cabs are so cheap and plentiful and parking is impossible or extortionate.

Yes, parking is difficult and the cabs are steady and yes, the traffic is unmerciful. But anyone who has driven in Cork or Dublin can do Manhattan with a blindfold.

Gobsmacked by the lack of any real challenge driving around the little island of mostly square blocks, and undeterred by the fact that I have not pedalled anything other than dodgy articles for years, I took to the bicycle.

Astonishment greeted my off-handed announcement to some friends who live in the city: "You didn't make the six o’clock news with the car, but we're looking at the top story here", laughing in my face as they mentally re-scheduled their week to include hospital visits or a quick trip to the auld sod for a funeral.

I set forth on my journey north along the East River. It was quiet enough, flat and almost free of traffic. After ten minutes my sense of adventure forced a left turn onto 34th street. One good thing about Manhattan is that there are not too many hills. A slight climb westward and I was passing the Empire State Building, nearly meeting a cab the hard way as my gaze was drawn irresistibly upwards. A few more blocks and I hang a right to head north for Central Park.

The park is a cyclists dream. Traffic is quiet (they do have special bicycle-only days, though I did not have the foresight to check), shanks mare and roller blades are the order of the day, save for those with dollars to spare to pay for a pony and trap. Here poodles lead their liveried dog-walkers equipped with silver poop scoopers as they stiffly stroll from the nearby exclusivity of 5th Avenue apartments. These dogs are treated better than their human neighbours a dozen blocks north in The Bronx. I soon tire of this tranquillity and set recklessly forth into the hubbub, eager for adventure.

Down Broadway, a nice slow hill, and into Times Square. When you drive through here you see little and hear nothing, being too preoccupied with avoiding all the traffic. At night the famous lights sparkle but in daytime you could be anywhere. Walking is no joy because the pavements are thronged with tourists asking directions. But on a two-wheeler it is a different story.

Traffic is sparse enough for me to use the middle of the road, an undertaking fraught with danger but spiced with adventure. Extra care is needed belting down the centre of Broadway, the wind in your face, making the best of the breaks in traffic; this is the way to see mid-town. Here, where Broadway crosses Fifth Avenue at the Flatiron building, my favourite in the city. Built in 1903, it is often incorrectly reported as having been the first steel-framed office block, though it was, for a short time, the tallest, as were dozens of others for brief periods before they were outgrown by their neighbours.

I travel all the way downtown until I get to Chinatown. Here it is time to trust the bike to a stout lock and a large lamp-post and have a look around the small shops and stalls.

Having bought all the five-dollar Cartier and Rolex watches I could use in a lifetime, I continue on my mission, across Delancey Street and into the Wall Street area, dodging limos and enjoying the exaggerated stature of the buildings created by the narrow streets. Some of the nicest buildings in Manhattan are here, including the old Courthouse and City Hall.

Onwards to Battery Park, the southern tip of Manhattan, looking out to the Statue of Liberty and Ellis Island in the bay, a fine place to have a rest after all that pedalling.

Having given up the bike on the streets of Dublin, mainly though fear, I can recommend that the Big Apple is best seen from the saddle.